Monday, October 15, 2012

WHAT IS HD AFTERALL?

The most basic
definition to begin with is: all digital formats with a resolution
greater than standard definition (SD) video are considered HD. The definition
gets more complicated as we consider HD as a set of digital video formats
rather than just one.

When
digital filmmakers talk about shooting in HD, they talk about following three
subsets: 720, 1080 and digital cinema. Scanning lines, Frames always is a part
of the discussion when we try to explain the three subsets as mentioned above,
so let’s understand them first:

FRAME

The Video track is actually made up of series of still images, and when they
are played in sequence, they appear to be moving. Frames of video are similar
to frames of a film, just that you can’t hold them in your hand and point
towards a light and see them. It’s not cellulose after all, but it works in the
same principle. Instead, you need a computer to decode the electronic information
that constitutes each frame and display it on a monitor.

The
number of still images, or frames per second is called as FRAME RATE. The
standard frame rate before the advent of sound in film used to be 14 – 18 frames
per second. In the mid- to late-1920s, the frame rate for silent films
increased to about 20 to 26 FPS. (Wikipedia). This change happened because it
needed to synched with sound. So, soon films were running at 24 frames per
second (fps). So, when you watch any of the silent films now, they appear to
run faster as more frames are running per second than what was originally shot.
Watch this restored version of “Alice in the Wonderland (1903)” http://youtu.be/zeIXfdogJbA

When
it comes to HD, there are different frame rates associated with it. It needed
to be compatible with American Analog
broadcast video, European analog broadcast video, so, here the subsets
of three potential sources of HD frame rates:

24p and 23.976p. Frame rates based on
Film. You will probably shoot in 24p, if you eventually want your footage shot
in Video to be transferred to Film eventually. To know more why or why not you
should go for 24 frames per second, see this tutorial by Larry Jordan: http://youtu.be/FO2dD4Z4oYI

29.97p, 30p, 59.94i, 60i, 59.94p, and
60p. Frame rates based on American television

25p and 50i. Frame rates based on
European television.

What
is ‘p’ and ‘i’ means, we will explore in the next section on scan lines, in my
next post.